Multi-touch mouse (for example, EvoMouse) is a type of handwriting system that allows a user to use his/or her finger gestures to control a computer system. This handwriting system, basically, is realized by first emitting a plane light parallel to a plane (for example, a desktop), capturing a light spot formed by the plane light reflected from an object (for example, a user's finger) on the desktop, and then calculating the object's position so as to determine a corresponding operation performed by the user.
However, the conventional handwriting system usually uses one light spot to calculate the object's position, so the handwriting system may not successfully distinguish the two operations “touch” and “hover” according to one light spot.